Loud knock when lowering electric roof

[EddySPalm]

There is one on each side... One is a little more stuck than the other, making the roof come down a little unevenly.

I actually got a reply on a fairly active spanish Marco Polo forum thread, saying that the knock is normal, and I shouldn't worry about it
That's good and all, but I'm not so sure the metal shavings and the uneven lowering of the roof is meant to be there....

 

[AlanC]

Not knowing the Marco Polo roof system, here is a guess.

The small piston (jpeg 03 and 16) seems to be operating a lock that comes into play probably to lock the roof in the raised position?

It has to release to let the roof drop and I imagine there is one on each side of the roof.

Could it be that, as one side ram that raises the roof and is working slower than the other it is out of sync with the lock release, and so the lock is wearing as it releases because is catches the lowering roof on the slow side, hence the metal filings?

If that is the case, then you should get the raising rams changed so that they operate in sync with each other again.

I may be completely 'out of sync here" of course.
Sorry couldn't resist that

Alan

 

[BikerGran]

So how will you keep the roof up if you disconnect the struts? Or how will you prevent it from coming crashing down and breaking something else?

 

[EddySPalm]

So how will you keep the roof up if you disconnect the struts? Or how will you prevent it from coming crashing down and breaking something else?

The same way most of you do, by keeping the hydraulic cylinders pressurized.
Or, like I suggested a few posts back; connect the gas struts when camping.

Edit: I am starting to wonder if you might have hydraulic cylinder/gas strut mixed up?

 

[EddySPalm]

Not knowing the Marco Polo roof system, here is a guess.

The small piston (jpeg 03 and 16) seems to be operating a lock that comes into play probably to lock the roof in the raised position?

It has to release to let the roof drop and I imagine there is one on each side of the roof.

Could it be that, as one side ram that raises the roof and is working slower than the other it is out of sync with the lock release, and so the lock is wearing as it releases because is catches the lowering roof on the slow side, hence the metal filings?

If that is the case, then you should get the raising rams changed so that they operate in sync with each other again.

I may be completely 'out of sync here" of course.
Sorry couldn't resist that

Alan

Alan, you might have a very good point, too! I can't see no obvious reason why one side is worse than another, and so far I haven't found any sort of adjustment to even out the forces from the latches either.
The roof raises and lowers perfectly straight with the gas struts disconnected though

 

[BikerGran]

Edit: I am starting to wonder if you might have hydraulic cylinder/gas strut mixed up?

I was confusing the gas strut with the hydraulic strut - it sounds hugely complicated and I hope I never have problems with my Cali roof!

 

[WelshGas]

I was confusing the gas strut with the hydraulic strut - it sounds hugely complicated and I hope I never have problems with my Cali roof!

No gas cylinder/strut and lock on the California. Obviously the MP doesn't monitor the Hydraulic pressure in the circuit, as the California does, and relies on a lock to keep it fully open. You may not have experienced the Hydraulic pump starting up at 3am to re-pressurise the circuit, yet. Seems to happen infrequently and when there are wide ambient temperature variations and the roof is up for an extended period - days.

 

[EddySPalm]

I was confusing the gas strut with the hydraulic strut - it sounds hugely complicated and I hope I never have problems with my Cali roof!

That is totally understandable! And I hope I never get any serious problems with mine either.
Man I wish there was a forum this active with lots of threads about my car

I'm gonna keep investigating the roof, both the problem and its function in general. The day something really bad happens I want to be somewhat prepared. And I will also try and see if anyone out there has converted their roofs to manual operation.

 

[WelshGas]

That is totally understandable! And I hope I never get any serious problems with mine either.
Man I wish there was a forum this active with lots of threads about my car

I'm gonna keep investigating the roof, both the problem and its function in general. The day something really bad happens I want to be somewhat prepared. And I will also try and see if anyone out there has converted their roofs to manual operation.

Have you checked here - Not trying to get rid of you as I have found this very interesting.

http://www.benzworld.org/forums/v-class/

 

[EddySPalm]

Have you checked here - Not trying to get rid of you as I have found this very interesting.

http://www.benzworld.org/forums/v-class/

Yeah I've seen it, but it barely has one page of threads with replies from 2017, and that's the whole v-class forum

 

[EddySPalm]

Maybe it's time to update this thread then:

I found a very active Spanish campervan forum, with lots of Marco Polo owners.

When I presented them to the "issue" I was just told "don't worry about it, they all make that noise"...
So it is basically like WelshGas and AlanC anticipated. The hydraulic rams brings the roof up into top position, whereas the gas struts engages a locking mechanism which keeps it there. To get the roof down, the hydraulic rams need to overcome the holding force of the locking mechanism, and when it does, that's when the loud bang appears.

It's been working just fine since 2017 and until now

 

[marcowithaviano]

Hi everyone, hi Eddy,
I hope you' re gonna read this since my 2005 Viano is doing exatcly the same since a couple days. I just wanted to know if everything's still allright with yours?
I found a French forum (link1) where they say you can first try to oil the small piston but i was wondering since they're gas piston maybe they shouldn't be oiled? and then put some silicone oil on the locking mechanicsm to keep the disengagement smoother. I'll try this in the weekend and update on the result.
In another post (link2) they show how to check and add some oil to the hydraulic system, more complicated but could be worth if the first step doesn't work (on page 3 there's some photos of the process). Anyway I have first to translate it correctly since my French is not perfect.
Let me know what you think.
thanks
Marco

 

[flying banana]

before you lower the roof. have you tried sending it up to take the weight off the locks ? maybe the roof is resting on the locks over time and causing the lock to go with a bang when you lower it. also as said, get some silicon sparay around the moving surfaces and parts. filing off any sharp edges will aid a smoother operation.

 

[EddySPalm]

Hi everyone, hi Eddy,
I hope you' re gonna read this since my 2005 Viano is doing exatcly the same since a couple days. I just wanted to know if everything's still allright with yours?
I found a French forum (link1) where they say you can first try to oil the small piston but i was wondering since they're gas piston maybe they shouldn't be oiled? and then put some silicone oil on the locking mechanicsm to keep the disengagement smoother. I'll try this in the weekend and update on the result.
In another post (link2) they show how to check and add some oil to the hydraulic system, more complicated but could be worth if the first step doesn't work (on page 3 there's some photos of the process). Anyway I have first to translate it correctly since my French is not perfect.
Let me know what you think.
thanks
Marco

Hey Marco,

Loving how your name coincides with the name of our vans

I have simply learned to live with the noise... It bugs me though, that you have actually NOT had the noise before. I was under the impression that it should be this way, especially since being told so on the above mentioned Spanish forum.

Since this thread, I have had to change one of the gas struts. It lost pressure, and wouldn't hold the roof up on its side of the van.
The left hydraulic cylinder also started leaking through last winter, and it sealed again when the weather got warmer. I had to do a refill and bleed though, and at some point I have to change that cylinder, or both of them.

 

[EddySPalm]

before you lower the roof. have you tried sending it up to take the weight off the locks ? maybe the roof is resting on the locks over time and causing the lock to go with a bang when you lower it. also as said, get some silicon sparay around the moving surfaces and parts. filing off any sharp edges will aid a smoother operation.

Good idea, though I think it's not possible (will try though!) as I think the roof has to go even lower than its "resting point" to disengage the "top position indication" switch (?). In other words, it will only allow you to bring it down

 

[marcowithaviano]

Good idea, though I think it's not possible (will try though!) as I think the roof has to go even lower than its "resting point" to disengage the "top position indication" switch (?). In other words, it will only allow you to bring it down

Thanks for the reply. but as said by Eddy I confirm you can't go up to disengage. The only way is to lower it to disengage.

Hey Marco,

Loving how your name coincides with the name of our vans

I have simply learned to live with the noise... It bugs me though, that you have actually NOT had the noise before. I was under the impression that it should be this way, especially since being told so on the above mentioned Spanish forum.

Since this thread, I have had to change one of the gas struts. It lost pressure, and wouldn't hold the roof up on its side of the van.
The left hydraulic cylinder also started leaking through last winter, and it sealed again when the weather got warmer. I had to do a refill and bleed though, and at some point I have to change that cylinder, or both of them.

ehehhe that's destiny. Yeah to me it's too loud the noise to live with it, either I don't think it's good for the roof.
Can I ask you where you find the replacement of the gas struts? it looks quite complicated to change... dont' you have to dismount everything in order to replace it?
Did you do the refill by yourself? I see on the other forum you have to dismount the right side of the van to get to the pump motor right? Was it complicated? Do you have any particular advice ?
Thanks for the quick reply.
Marco

 

[EddySPalm]

I believe I took measurments of the gas struts and found ones with similar total length, stroke length and spring force on an online shop in Norway. Probably www.gassfjaershop.no!

The replacement was a bit of a pain, yes. To not having to dismantle the hydraulic mechanism as a whole, I had to drill out a special rivet on one end of the gas strut. This was not a problem, but getting new ones from Mercedes certainly was! I ended up maching a special screw/nut combination to size, which fit perfectly, and makes for easier service later. If you ever go that route, let me know, and I will make up a few for you also

Refilling the hydraulic fluid system was really not complicated. Dismantlig the plastic panels in the interior was the hardest part, maybe also refilling the reservoir without spilling. Have spare plastic plugs for the panels ready for reassembly, you will definitely break one or two. The bleeding part was super simple: just fill up the reservoir little by little, while raising and lowering the roof a few times to get rid of any air in the system.

I must say I am not looking forward to when the day comes to change the cylinders. I can see that it has been leaking a little this winter also, but not as much as last winter. I spent a LOT of time trying to find ways to replace the seals on the cylinders, I even spoke to the manufacturer of the cylinders, but found out they are really custom made cylinders that is not even interchangeable with ones from a California... Keep your eyes out for parted Marco Polos with easy-up roof Think I have a thread on here regarding the issue.

 

[marcowithaviano]

Hi Eddy,
thank you very much for your help. I tried to put some oil on the locking mechanism but it didn't changed that much. I noticed that two gas straw are not exactly in the same position when locked, one stays way more stretched then the other but I can't figure if the problem is in the gas straws or in the hydraulic system, do you think there could be an asymmetry in the cylinders and the refilling the system could solve the problem?
When you have time can you send me a photo of the new gas straw.
M

 

[EddySPalm]

As far as I understand, an uneven roof can be caused bu two things:

1. If your roof is uneven right after raising it, it is caused by the hydraulic cylinders not pushing evenly, and has nothing to do with the gas springs. I sometimes have to to a sequence of raising the roof, lowering it a little bit, and then raising it again. I don't think I have had to do this after last years system bleed, though. Also, if you're parked unevenly (not level), my experience is that it greatly affects the evenness of the roof when being raised.
2. If the roof becomes uneven after some time, then it is because one of your gas springs (straws) have not engaged properly. Maybe it has lost some or all of its pressure. By looking at the safety latches that attaches to the gas spring, you are able to see if one is more engaged than the other. By experience, if one out of two gas springs is not engaging the safety latch, the roof will become very uneven over the course of a night, and i find it quite dangerous actually, especially if the kids are sleeping up there.

 

[EddySPalm]

When it comes to the knocking noise, I am still under the impression that it is normal, but maybe I'll do some research on my own in the coming time. There is a Marco polo owners forum which is not very active, but one might get lucky and find someone on there with experience with a W639 with the "easy-up" mechanism.